Stem cell-related proteins C-KIT, C-MYC and BMI-1 in juvenile nasopharyngeal angiofibroma--do they have a role?

Juvenile nasopharyngeal angiofibroma (JNA) is a highly vascular tumour, occurring almost exclusively in adolescent males. Histogenesis of JNA remains unclear, two optional theories proposing either fibrous or vascular tissue as the tissue of origin. Stem cell-related proteins have been discussed to possibly participate in the growth of these tumours. In our study, we reviewed retrospective clinicopathological data of 26 JNA patients. By immunohistochemistry, we investigated the cellular distribution and expression levels of stem cell-related proteins C-KIT, C-MYC and BMI-1 and their correlation with cell and vessel density of the tumour. Contrary to earlier reports, we detected C-KIT expression in addition to stromal cells also in endothelial cells. The C-KIT expression was more dominant in slit vessels than large vessels. A significant correlation was found between endothelial immunoexpression of C-KIT and cellular density of the tumour. C-MYC and BMI-1 expression was detected in stromal cells only. Due to our finding of C-KIT expression in both stromal and endothelial cells and the strong correlation between the endothelial C-KIT expression and cellular density, we suggest that, besides the stromal tissue, the vascular component might take part in the neoplastic growth of JNA.